UIM 8.51 and above
1. Move robots from the hub to be removed.
2. Delete all queues referencing the secondary hub.
3. In the nas probe on the primary hub, delete all forwarding & replication referencing the secondary hub.
4. In the nas probe on the primary hub, delete Name Services entry for the secondary hub.
5. In the hub probe on the primary hub, remove the entry for the secondary hub from the Hubs tab.
6. Uninstall all remaining UIM software from the secondary hub.